package com.example;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.ServerSocket;
import java.net.Socket;

/**
 * @author zhouyp
 * @program tp-monitor
 * @description
 * @create 2020-07-13
 */
public class RpcFramework {

	/**
	 * 暴露服务
	 *
	 * @param service 服务实现
	 * @param port    服务端口
	 * @throws Exception
	 */
	public static void export(final Object service, int port) throws Exception {
		if (service == null)
			throw new IllegalArgumentException("service instance == null");
		if (port <= 0 || port > 65535)
			throw new IllegalArgumentException("Invalid port " + port);

		System.out.println("Export service " + service.getClass().getName() + " on port " + port);

		ServerSocket server = new ServerSocket(port);
		while (true) {
			try (final Socket socket = server.accept()) {
				final Runnable runnable = () -> {
					try (ObjectInputStream input = new ObjectInputStream(socket.getInputStream())) {
						String methodName = input.readUTF();

						Class<?>[] parameterTypes = (Class<?>[]) input.readObject();
						Object[] arguments = (Object[]) input.readObject();

						try (ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream())) {
							Method method = service.getClass().getMethod(methodName, parameterTypes);
							Object result = method.invoke(service, arguments);
							output.writeObject(result);
						}
					} catch (Exception ignored) {
					}
				};
				new Thread(runnable).start();
			}
		}
	}

	/**
	 * 引用服务
	 *
	 * @param <T>            接口泛型
	 * @param interfaceClass 接口类型
	 * @param host           服务器主机名
	 * @param port           服务器端口
	 * @return 远程服务
	 * @throws Exception
	 */
	@SuppressWarnings("unchecked")
	public static <T> T refer(final Class<T> interfaceClass, final String host, final int port) throws Exception {
		if (interfaceClass == null)
			throw new IllegalArgumentException("Interface class == null");
		if (!interfaceClass.isInterface())
			throw new IllegalArgumentException("The " + interfaceClass.getName() + " must be interface class!");
		if (host == null || host.length() == 0)
			throw new IllegalArgumentException("Host == null!");
		if (port <= 0 || port > 65535)
			throw new IllegalArgumentException("Invalid port " + port);
		System.out.println("Get remote service " + interfaceClass.getName() + " from server " + host + ":" + port);

		return (T) Proxy.newProxyInstance(interfaceClass.getClassLoader(),
				new Class<?>[]{interfaceClass}, new InvocationHandler() {
					public Object invoke(Object proxy, Method method, Object[] arguments) throws Throwable {
						try (Socket socket = new Socket(host, port);
						     ObjectOutputStream output = new ObjectOutputStream(socket.getOutputStream())) {
							output.writeUTF(method.getName());
							output.writeObject(method.getParameterTypes());
							output.writeObject(arguments);
							try (ObjectInputStream input = new ObjectInputStream(socket.getInputStream())) {
								return input.readObject();
							}
						}
					}
				});
	}

	public interface HelloService {
		String hello(String name);
	}

	static class HelloServiceImpl implements HelloService {
		public String hello(String name) {
			return "Hello " + name;
		}
	}

	static void provide() throws Exception {
		HelloService service = new HelloServiceImpl();
		RpcFramework.export(service, 1234);
	}

	static void consume() throws Exception {
		HelloService service = RpcFramework.refer(HelloService.class, "127.0.0.1", 1234);
		for (int i = 0; i < Integer.MAX_VALUE; i++) {
			String hello = service.hello("World" + i);
			System.out.println(hello);
			Thread.sleep(1000);
		}
	}
}
